System.AccessViolationException in CSharp-Wrapper for CPP

We want to have a csharp wrapper for an exisiting dll and now trying to write a wrapper for the dll to wrap it in csharp.

c++ code:

        extern "C" __declspec(dllexport) int test(unsigned char* initValue)
        {   
            //// Get a handle to the DLL module.
        
            HINSTANCE hinstLib = LoadLibrary(TEXT("test.dll"));

            return 0;
        }

The C# wrapper:

        public class TestWrapper
        {
      
            [DllImport("cppWrapper.dll", CallingConvention = CallingConvention.Cdecl)]
            public static extern int test(byte[] outInitValue);
        }

But go this exception:

System.AccessViolationException: 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'

"Test.dll" is a WIN32 (x86) DLL but we changed the build type to x86 but that didn´t work. Without LoadLibrary(TEXT("test.dll")); everything works fine.